Documents of an extremely sensitive nature and items having a high proprietary value often need to be stored within a safe or other structure. The structure typically includes a lock mechanism, and the structure is generally designed to be accessible only by a select few individuals who are entrusted with a predetermined combination code that facilitates the unlocking of the mechanism. As more sophisticated lock picking and security feature defeating methods have been developed, the types of lock mechanisms have also developed to become more robust and secure.
Electro-mechanical locks, such as used on safe doors or other cabinets and structures needing security typically include wiring extending between inner and outer portions of the lock. For example, an outer portion of the lock may be a housing with a dial and/or another user input device for allowing the user to input a combination code to the lock. The dial may be used both for inputting the combination and, after the correct combination code is input, for then retracting the lock bolt. The wiring extends through the door, or other access member of the structure such as a cabinet drawer panel and carries voltage for powering one or more inner lock components and for carrying electronic signals such as those used in connection with the combination code. The electrical wiring, such as a ribbon cable in one example, is susceptible to damage. Moreover, because the doors or other access members of different lock installations will have different thicknesses, this part of the lock installation process can be tedious as a result of managing the length and positioning of the electrical wiring as well as the matching of the length of these components to the thickness of the door/lock.
In some conventional lock designs, two thin-walled stainless steel tubes are used in a tube-within-a-tube configuration (hereinafter “double tube arrangement”) and a ribbon cable is located between the two tubes. The ribbon cable is positioned to extend lengthwise along the inner tube and the outer tube is then inserted over the ribbon cable in a generally concentric (or tube-within-a-tube) fashion to form the double tube arrangement, with any excess of the ribbon cable projecting from the tube typically stored within the outer lock housing. By placing the ribbon cable between the steel tubes, the ribbon cable is configured to be protected from abrasion and any RF emissions are contained/protected. The lock spindle extends through the inner tube from the outer lock housing to the inner lock housing. These tubes each must be cut to a precise length matching the thickness of the door on which the lock is being installed.
This cutting and installation of the lock is a difficult process for two reasons. First, the measurement must be exact and, second, the tubes have a very thin wall and therefore a very fine tooth saw must be used to cut them. It may also be required to supply a specially-formed holding block for securely holding the components to be cut with the saw, and a grinding stone to remove any burrs or discontinuities formed during the cutting process. Too often, the relatively fragile ribbon cable located between the tubes in the double tube arrangement gets damaged during the cutting or grinding steps and must be replaced during the installation process. In general, such errors can add too much time, expense and complexity to the installation process.
Consequently, it would be desirable to improve the design of the electro-mechanical lock to provide the electrical wiring or communication in a more reliable and cost-efficient manner.